Similar results were reported by Ågerstam et al. (38), where NOD/SCID mice engrafted with human AML cells showed reduced frequency of leukemic cells in BM after treatment with an antibody against a stem cell antigen (anti-IL1RAP) but also developed extensive myeloid sarcoma that was rate-limiting for survival. The gene discussed is IL1RAP; the disease is acute myeloid leukemia.